The traditional power transmission method achieves power transmission through an electrical connector such as a plug-socket. This transmission method is simple, convenient, but is only suitable for small-current transmission scenarios. In large-current transmission scenarios, it requires working together with the arc-extinguishing method, and the conductor is exposed, which is unsafe. Multiple plugging may cause mechanical wear and loose contact and the electric power cannot be effectively transmitted. The contactless transformer separates its primary and secondary coils by a certain distance and achieves power transmission through the magnetic coupling. The wireless charging system technology uses the advantage of the contactless transformer to address the defect that the traditional wire directly contacts the supply power.
The air gap between the primary and secondary coils of a common transformer is close to zero, the power transferred from the primary coil to the secondary coil is calculated based on the turn ration of the primary coil to the secondary coil. While the air gap between the primary coil and the secondary coil of a contactless transformer is relatively large, and the air gap significantly affects the parameters of the contactless transformer, especially the leakage inductance and coupling system of the contactless transformer, and further affects power transmission of the contactless transformer. For different air gap sizes, the contactless transformer needs to use different parameter settings.
Similarly, in the wireless charging system, when the primary and secondary coils of the contactless transformer cannot be perfectly aligned, that is, when there is a certain misalignment between them, it will also affect the transmission efficiency of the system. For a different size of the misalignment, the contactless transformer also needs to use a different parameter setting.
Therefore, in order to improve the power transmission efficiency of the contactless transformer or adaptively optimize the power transmission, it needs to detect the sizes of the air gap and misalignment between the primary and secondary coils.